K2-233 c
Astrophysical Synthesis & Habitability Characterization
K2-233 c is a confirmed super-earth exoplanet orbiting the star K2-233, located approximately 220.2 light-years (67.51 parsecs) from the Solar System. First announced in 2018 by K2 using the Transit detection technique (producing an estimated primary transit depth of 0.027% across the stellar disk), this world measures 1.272 Earth radii and has a measured mass of 4.6 Earth masses. Combining its mass and radius yields a mean bulk density of 12.32 g/cm³ (an iron-enriched, high-compression rocky core), a surface gravity of 2.84 g⊕ (27.85 m/s²), and an escape velocity of 21.3 km/s.
In its orbital architecture around K2-233, K2-233 c completes one full revolution every 7.06 Earth days at a semi-major axis of 0.0664 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 102.3 km/s (compared to Earth's 29.8 km/s). The orbit is modeled as circular (e = 0.00), maintaining a constant stellar distance throughout its year.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 794 K (+521°C / +970°F) and receiving 66.20 S⊕ (~90,098 W/m²), K2-233 c orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star K2-233 is classified as an orange K-type star of spectral type K3 with an effective photospheric temperature of 4,796 K, a radius of 0.71 R☉, a mass of 0.79 M☉, an estimated bolometric luminosity of 0.239 L☉. Stellar evolution modeling indicates an estimated stellar age of 0.36 Gyr and a metallicity of [Fe/H] = -0.082 dex (near-solar heavy-element abundance). From Earth, K2-233 shines at apparent V-band magnitude 10.883 (faint and requiring research-grade or CCD telescopic photometry) in the Southern celestial hemisphere. The K2-233 system is a multi-planet architecture hosting 3 confirmed worlds, with K2-233 c sharing its stellar neighborhood alongside K2-233 b, K2-233 d.
Methodology: Computed using the Schulze-Makuch et al. (2011) weighted metric comparing physical interior (radius, estimated density) and surface thermal regime (escape velocity, equilibrium temperature).
Discovery Facility: K2 · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | K2-233 |
| Spectral Type | K3 |
| Effective Temp (Teff) | 4,796 K |
| Stellar Radius | 0.7100 R☉ |
| Stellar Mass | 0.7900 M☉ |
| Bolometric Luminosity | 0.239 L☉ |
| Metallicity [Fe/H] | -0.082 dex |
| Stellar Age | 0.360 Gyr |
| Apparent Magnitude | V: 10.883 · G: 10.419 |
| System Architecture | 1 Star, 3 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.066400 AU |
| Orbital Period | 7.06 days |
| Mean Orbital Velocity | 102.3 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 89.5700° |
| Mean Bulk Density | 12.32 g/cm³ (21.3 km/s vesc) |
| Insolation Flux | 66.2000 S⊕ (~90,098 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 220.200 LY (67.506 pc) |